A: L.C., the fact that your truck runs fine once it's warmed up, leads me to believe that something could be wrong with the coolant temperature sensor. This sensor tells the engine control computer the temperature of the engine so the computer will inject the proper amount of fuel into the air-fuel mixture. The coolant temperature sensor is a temperature-sensitive variable resistor (thermistor) whose internal resistance changes based on temperature.

Most typically, this type of sensor has higher internal resistance when cold and lower resistance when warm. If the sensor's internal resistance is lower than it should be when the engine is actually cold, the computer will think the engine is warm and not inject enough fuel. A scan tool can be plugged into your Silverado's diagnostic connector to see what the engine control computer sees. For instance, if the vehicle has been sitting outside overnight, before starting the engine, with the key on and the scan tool hooked up, the coolant sensor reading should be the same as the outside air temperature. If not, the sensor or its wiring could be the problem. It's also possible that the engine control computer could be faulty. Take your truck to a shop that specializes in engine performance issues and you'll want to leave it overnight so they can experience the symptoms firsthand.

Q: I have a '92 Buick Roadmaster Estate Wagon. I'm interested in increasing my vehicle's power and performance. After ensuring that the drivetrain and chassis can handle that, I'd like to know what your suggestions would be. In addition, I would like to replace the steering wheel with something that is more aesthetically pleasing as the horn buttons have fallen out. I'd like to go "retro" in place of buying a new steering wheel with an airbag. -- L., Chicago

A: L., your question is difficult to answer. What upgrades you make to an engine depend on what goals you have in mind and whether the car will be street-driven, or set up for the track. Major upgrades to the engine generally require upgrades to the transmission, driveshaft, differential, suspension, tires, and brakes.

If you're just looking to operate on the street and want to keep things rolling for a long time, you'll probably want to take the engine out and have it rebuilt. And that gives you a multitude of options. You may want to increase the displacement by putting in a different crankshaft. That will require opening up the intake and exhaust ports, putting on a bigger intake manifold and exhaust manifold, possibly headers. That requires upgrades to the fuel delivery system.

My best advice would be to consider a performance kit, which has been designed by engineers and usually comes with everything you'll need. You can find out about these kits by visiting your local auto parts store or searching online. The auto parts store should also be able to help you find different steering wheels, but if you ever sell the car, I'd recommend putting the one with the airbag back on to avoid any potential legal issues down the road.

AutoAdviser: Ira Siegel is an Automotive Instructor and ASE Certified Master Auto Technician. If you have auto-related questions for Ira Siegel you can call and leave your questions at the Auto Adviser Hotline at 708-633-6839 or e-mail a question to Autoadvisr@aol.com.